If you’re familiar with bougainvillea, you’re already imagining their vibrant Fuschia, purple, peach, or white bracts. You may also be aware that they’re one of the most commonly grown ornamentals in tropical climates.
Their flowers, foliage, and growing habits are fairly similar to those of four o’clock, which means that bougainvillea is very easy to grow and train, as long as you provide them with the right conditions.
When those conditions become less than ideal, you may find your bougainvillea not blooming. Keep reading to learn why this happens and what you can do to get your bougainvillea back to being the prolific bloomer that it is.
- When Should Bougainvillea Bloom?
- Reasons Why Your Bougainvillea is Not Blooming
- Bougainvillea Not Flowering FAQ
- Final Thoughts: How to Get Bougainvillea to Bloom
When Should Bougainvillea Bloom?
A Bougainvillea will bloom profusely and produce lush foliage when all its needs are met. They also perform better when properly supported, as well, and not allowed to become a tangled, unpruned mess on the ground.
Yet, bloom times are not dependent on these factors, alone. It may be surprising to note that while Bougainvillea thrives in intense sunshine, flowering is most often dictated by the seasons, especially when days are less than 12 hours long.
This is good news for those who grow Bougainvillea in warm and cold climates. In warm zones, these climbers will bloom when it seems all other flowering plants are going dormant. In cold zones, your bougainvillea may bloom continuously, indoors, due to lower light availability.
Bougainvillea Flowering Season
This colorful show is actually produced by bracts, leaves with brightly colored pigmentation, which bud on new wood. Flowers are tiny and white and appear in the center of clustered bracts.
In hardiness zones 10 and 11, this vigorous vine delivers three bloom sequences, in spring, summer and fall. Followed by a seemingly more abundant one in winters that remain above 60°F.
In all other zones, Bougainvillea will bloom the same way, in spring, summer, and fall. In winter, however, where these need to be wintered over indoors, blooms may not appear, if they’ve gone dormant.
Reasons Why Your Bougainvillea is Not Blooming
If you find your Bougainvillea isn’t blooming, figuring out why is as easy as narrowing down each aspect of their care, to determine what needs improving. The following will have a direct effect on plant performance:
- Too much water
- Too much fertilizer
- Not enough direct sunlight
- Slow draining soil
- Outdoor temperatures are too cold
Bougainvillea has very thin roots that can detect the slightest hint of water and use it efficiently. Over-watering will have detrimental effects.
Over-fertilizing will refocus the plant’s energy in directions it wouldn’t naturally go. This results in diminishing the number of bracts and blooms.
Too much shade means not enough sunlight to trigger healthy growth and Bracht production.
Too Much Water
All living things need water. But, Bougainvillea has adapted, over time, to be highly drought tolerant. So, they don’t need a lot to grow lush and luxurious.
Their roots are long and thin, absorbing small amounts of moisture at a time, to accommodate for the lack of abundant water in their native habitat.
Water your Bougainvillea deeply, yet infrequently. Just as you would other dry climate plants, like lavender, rosemary, and other Mediterranean herbs. How much you water will depend on the size of your plant.
Over-watering is the fastest way to stress out any Bougainvillea cultivar. Resulting in plant failure and you missing out on a beautiful plant.
What Do Overwatered Bougainvillea Look Like?
It’s challenging to tell what’s wrong by looking at a Bougainvillea. But, over-watering is unfortunately common and has some pretty distinct “tell-tale” signs.
The most obvious one is a lack of blooms. Lots of green leaves will soon drop, followed by fungal diseases and root rot. A good rule of thumb to follow is:
“Few leaves, but some weak bracts equals not enough water. Lots of green leaves, but little color means too much water. A combination of healthy leaves and bracts and bingo! You’ve got the mix just right.”
How Often to Water a Potted Bougainvillea
Because over-watering is such an issue, it’s best to let plants tell you when they need watering. Visibly slow growth will be the first sign. But, testing the soil around the plant with your finger is faster and easier, on you and your Bougainvillea. If it’s dry down 3-4 inches, it’s time to water.
This method is effective for both ground and pot-planted Bougainvillea. But, keep in mind that the soil around potted plants will dry out faster.
Wrong Planting Location
Along walls and fences are classically elegant as well as the most successful places to train Bougainvillea, especially when planted in direct sun. Extended exposure to warm sunlight is what triggers Bracht and bloom production in Bougainvillea.
If planted in an inappropriate location, like one with too much shade, you may get lots of lovely, green foliage. But, that’s it. Virginia creeper, ivy, or similar would be happier in that spot.
For optimal flowering, plant your bougainvillea in a sunny spot that receives at least 6 hours of bright, direct sun. Small, potted bougainvillea are easy to move around to catch the best light (indoors and out) for improved growth and performance.
Leaves Turning Yellow & Falling Off
We’ve talked about leaf drops as a symptom of over-watering. If you’re confident that your watering practices are on point, but still see this happening, it could also be the result of insufficient sunlight.
Bougainvillea uses sunlight to photosynthesize and produce food for themselves using the chlorophyll cells in their leaves. These cells give leaves their green color.
In low light, chlorophyll cells don’t absorb enough light to sustain themselves and they die. Causing the leaves to yellow and fall off.
Incorrect Soil Conditions
Suitable soil structure goes hand-in-hand with effective watering practices. These prolific bloomers do so when planted in loose, well-draining, sandy soil.
If the soil around the base of your Bougainvillea gets compacted, it’s unlikely water and nutrients will even reach the roots. If it has water-retaining properties that are too strong (like perlite, vermiculite, or peat), this will create a water-logged environment that may result in your Bougainvillea failing.
For dense or clay-based, adding sand to your initial planting hole will improve drainage.
Planting location is also associated with soil conditions. Low-lying areas hold more groundwater than higher elevations, which are more suitable for Bougainvillea.
Just as Bougainvillea roots are sensitive to water, they’re also overstimulated by too much fertilizer.
Since their colorful bracts are technically not flowers, high amounts of phosphorus and potassium will not encourage blooming.
Instead, forced foliage growth distresses the plant by overpowering its ability to produce bracts and blooms.
A soil test will determine what your soil is already providing. A mild 10-10-10 NPK, when applied appropriately, can replenish whatever is needed.
In warm climates, this can be done at any time throughout the year. In cold climates, fertilizing should cease in late summer, to prevent any new growth that may be damaged while the plant is dormant.
Best Fertilizer for Bougainvillea
The conundrum is that while Bougainvillea is sensitive to fertilizer, they’re also considered heavy feeders. The solution is to provide slow and steady access to nutrients in the form of slow-releasing granules or spikes.
A well-balanced NPK will maintain equal nutrient availability, supporting lush foliage growth and lots of cascading color.
Fertilizing Bougainvillea isn’t always necessary. But, when it is, a 10-10-10 NPK will be enough to keep your bougainvillea happy. In poor soil, a 20-20-20 NPK can initially increase nutrient availability to the required levels, but it must be a controlled-release product.
Bougainvillea is tough shrubs and can actually withstand some pretty hard pruning, once they mature. Overgrown bushes can be cut back to just 2-4ft above the soil line, to encourage vigorous new growth.
However, effective pruning, for increased color, is all about timing. If you wait until mid-spring, when new buds have already formed, that splashy Bougainvillea show will be delayed until the following year.
Pruning too early, like in late fall or early winter, risks low temperatures killing the new growth that immediately emerges after pruning. It’s the new growth on which new bract and flower buds would otherwise form.
So, if Bougainvillea is always blooming, when can you prune them?
How to Prune For Maximum Flowering
Pruning can be done any time during a pause in flowering. Potted bougainvillea that is wintered over indoors should be pruned in early spring, as temperatures begin to rise. Just before new leaves begin to bud.
Any vines, on mature plants, that have grown too lanky or weak, should be pruned back by one-third of their total length. Making the cut just past a bud node. Young plants should be cut closer to the base to increase bushier growth.
Pot Size is Too Big
As with any plant, pot size is vital to proper water and nutrient absorption.
Too big, and water and nutrients flow right through and drain out, without the roots ever having detected them. Too small, and the root ball may grow too dense to absorb anything.
The best starting pot will be clay, terracotta, or unglazed ceramic with a 12” lip diameter and equal depth. Naturally, drainage holes in the bottom are a must.
As your plant grows into the pot, it may flower more. This is the plant’s “stress response” to being constricted. But, once it outgrows that pot, it must be moved to one that is roughly 1-½” bigger.
Bougainvillea Not Flowering FAQ
Final Thoughts: How to Get Bougainvillea to Bloom
When we’re happy, we bloom where we’re planted. Your Bougainvillea is no different. With the right amount of water and fertilizer, it will have what it needs to keep those all-important, metabolic processes running. When you plant it in a location with lots of warm, direct sunlight and loose, sandy soil, your Bougainvillea will steer many of those processes in the direction of producing lots of brilliant colors and a healthy, low-maintenance, vining shrub for you.